The invention is related to the field of aligning machine components, in particular, to the alignment of an interconnection between a main unit of an assembly and a removable subassembly.
Statement of the Problem
Modular design and construction of machines and electronic instruments provides numerous advantages. It allows separate fabrication of individual units and subassemblies. Further, it allows convenient removal of an individual unit or subassembly from a system, and its efficient replacement by a substitute unit or subassembly. Modular operation is particularly useful in a system that includes a plurality of identical or similar functional modules that may not be shut down for repair or maintenance.
Improper or imprecise alignment of a modular unit or subassembly during its replacement into a system commonly interferes with proper operation or causes damage. For example, modular design and operation of a system typically requires one or more forms of interconnection between the system and separate units and subassemblies. A common form of electrical interconnection includes a plug having a plurality of pins that is inserted into a jack having corresponding pin-holes. Improper alignment commonly causes unsatisfactory electrical interconnection. It also commonly damages plug pins and other components of interconnection devices.
Modular assembly of a system typically requires mechanical support of a modular subassembly. Improper or insecure mechanical alignment of a modular subassembly in the system commonly results in improper operation or damage to components.
U.S. Pat. No. 5,602,717, issued Feb. 11, 1997 to Lesham et al., discloses a data storage mechanical interlock subassembly including a first extending rigid pin for pre-aligning, and a second extending rigid pin for fine aligning. The disclosed pins are apparently conical, and the apertures for accepting the pins are apparently circular. U.S. Pat. No. 5,325,263, issued Jun. 28, 1994 to Singer et al., discloses locating pins having a tapered tip intended to easily slide into a locating member or hole. The locating pins preferably have a criss-cross cross-sectional area. The locating pins are apparently individual pieces connected to a chassis or frame. The locating holes for accepting the pins are apparently circular. U.S. Pat. No. 6,202,291 B1, issued Mar. 20, 2001 to Toedtman, discloses an alignment device including single-plane alignment tips formed in a triangle or wedge shape. The tips are separate pieces attached to signal or power alignment plugs.
The invention helps to solve some of the problems mentioned above by providing a system for aligning two units of a modular system, comprising: a projection extending from a base region of a first unit, the projection having a first planar portion and a second planar portion; and a receptacle in a mounting region of a second unit, the receptacle having a shape for receiving the projection and engaging the first and second planar portions. The first planar portion and the second planar portion form an intersection with an intersection angle in a range of from 10xc2x0 to 170xc2x0. The projection extends in a direction substantially perpendicular to a base panel in the base region. The projection has a base end proximate to the base region and a tip end distal from the base region, and the tip end is tapered so that the base end has larger dimensions than the tip end. Typically, the first planar portion and the second planar portion are substantially perpendicular to each other; that is, the intersection angle between the first planar portion and the second planar portion is typically about 90xc2x0. Typically, the receptacle is a slot in the mounting region.
In preferred embodiments, the tip end of the projection fits loosely in the receptacle, and the receptacle holds the base end of the projection tightly when the projection is inserted fully into the receptacle such that the base panel of the first unit is in contact with at least a portion of a mounting face of the second unit. The intersection of the first planar portion and the second planar portion forms a substantially linear axis perpendicular to the base region. An advantage of a system in accordance with the invention is that the receptacle engages the first planar portion and the second planar portion to prevent rotation of either the first unit or second unit around the linear axis when the projection is inserted fully into the receptacle. In certain embodiments, the receptacle tightly engages the first planar portion and a second planar portion at the base end, but does not tightly engage the intersection of the first and second planar portions. Typically, at least a portion of the base region of the first unit comprises a rigid material, and the projection is an extension of the rigid material. In typical embodiments in accordance with the invention, the first unit has a shape of a rectangular box, and the base panel is a rectangular side of the box. Typically, the first unit comprises a housing of rigid material, a housing includes the top, the bottom, a first side and a second side, and the projection is an extension of the housing. Typically, the rigid material comprises sheet metal. Typically, the projection is an extension of a corner region of the housing, and the first planar portion and the second planar portion are formed by a fold in the projection. A system in accordance with the invention may comprise one or a plurality of projections and mating receptacles.
A system in accordance with the invention is particularly useful for aligning a removable subassembly in a main assembly. On-line replaceable modular subassemblies are quickly and properly aligned for interconnection with main assembly units. For example, a system in accordance with the invention is useful for reliable and proper aligning of redundant power supply subassemblies with a computer server.